signal-desktop/libtextsecure/stringview.js

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(function() {
'use strict';
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window.StringView = {
/*
* These functions from the Mozilla Developer Network
* and have been placed in the public domain.
* https://developer.mozilla.org/en-US/docs/Web/API/WindowBase64/Base64_encoding_and_decoding
* https://developer.mozilla.org/en-US/docs/MDN/About#Copyrights_and_licenses
*/
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b64ToUint6: function(nChr) {
return nChr > 64 && nChr < 91
? nChr - 65
: nChr > 96 && nChr < 123
? nChr - 71
: nChr > 47 && nChr < 58
? nChr + 4
: nChr === 43
? 62
: nChr === 47
? 63
: 0;
},
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base64ToBytes: function(sBase64, nBlocksSize) {
var sB64Enc = sBase64.replace(/[^A-Za-z0-9\+\/]/g, ''),
nInLen = sB64Enc.length,
nOutLen = nBlocksSize
? Math.ceil(((nInLen * 3 + 1) >> 2) / nBlocksSize) * nBlocksSize
: (nInLen * 3 + 1) >> 2;
var aBBytes = new ArrayBuffer(nOutLen);
var taBytes = new Uint8Array(aBBytes);
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for (
var nMod3, nMod4, nUint24 = 0, nOutIdx = 0, nInIdx = 0;
nInIdx < nInLen;
nInIdx++
) {
nMod4 = nInIdx & 3;
nUint24 |=
StringView.b64ToUint6(sB64Enc.charCodeAt(nInIdx)) << (18 - 6 * nMod4);
if (nMod4 === 3 || nInLen - nInIdx === 1) {
for (nMod3 = 0; nMod3 < 3 && nOutIdx < nOutLen; nMod3++, nOutIdx++) {
taBytes[nOutIdx] = (nUint24 >>> ((16 >>> nMod3) & 24)) & 255;
}
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nUint24 = 0;
}
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}
return aBBytes;
},
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uint6ToB64: function(nUint6) {
return nUint6 < 26
? nUint6 + 65
: nUint6 < 52
? nUint6 + 71
: nUint6 < 62
? nUint6 - 4
: nUint6 === 62
? 43
: nUint6 === 63
? 47
: 65;
},
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bytesToBase64: function(aBytes) {
var nMod3,
sB64Enc = '';
for (
var nLen = aBytes.length, nUint24 = 0, nIdx = 0;
nIdx < nLen;
nIdx++
) {
nMod3 = nIdx % 3;
if (nIdx > 0 && (nIdx * 4 / 3) % 76 === 0) {
sB64Enc += '\r\n';
}
nUint24 |= aBytes[nIdx] << ((16 >>> nMod3) & 24);
if (nMod3 === 2 || aBytes.length - nIdx === 1) {
sB64Enc += String.fromCharCode(
StringView.uint6ToB64((nUint24 >>> 18) & 63),
StringView.uint6ToB64((nUint24 >>> 12) & 63),
StringView.uint6ToB64((nUint24 >>> 6) & 63),
StringView.uint6ToB64(nUint24 & 63)
);
nUint24 = 0;
}
}
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return sB64Enc.replace(/A(?=A$|$)/g, '=');
},
};
})();